Fabricating Bifunctional Co-Al₂O₃@USY Catalyst via In-Situ Growth Method for Mild Hydrodeoxygenation of Lignin to Naphthenes

To enhance the catalytic activity and stability of metal catalysts in the hydrodeoxygenation of lignin derivatives into naphthenes, a bifunctional Co-Al2O3@USY catalyst was fabricated by the reduction of CoAl layered double hydroxide in-situ grown on the USY zeolite. In the hydrodeoxygenation of guaiacol, a 100.0 % conversion with cyclohexane yield up to 93.6 % was achieved at 180 degrees C, 3 MPa for 4 h, which should be the hitherto lowest reaction temperature that has been reported over Co-based metal catalysts. This catalyst was also relatively stable with 5 runs and exhibited excellent catalytic performance in the hydrodeoxygenation of other lignin model compounds and even real lignin feedstock into naphthenes. The high-efficiency of Co-Al2O3@USY was attributed to the synergistic effect between well-dispersed small Co nanoparticles and abundant acidic sites on the USY surface, while the outstanding stability was attributed to the anchoring effect of Al2O3 matrix to Co nanoparticles which avoided the leaching of Co species and particle agglomeration. This work provides a potential strategy for the design of an efficient and stable catalyst for lignin utilization.